82 GEOLOGICAL SURVEY OF THE TERRITORIES. 
imens before referred to, this form has been found only at Point of Rocks 
Station, Union Pacific Railroad, Wyoming, in the upper strata of the 
Bitter Creek series of the Laramie Group, a few hundred feet above 
those in which the Mr. Meek’s types of O. undifera were discovered. 
CORBULA PYRIFORMIS Meek. 
This species is peculiar to the Bear River Laramie series, and at most 
of the known localities at which those strata are exposed it is one of 
the most abundant forms. C. englemannt Meek, an associated form, I 
regard as only a variety of C. pyriformis. Both forms are described in 
vol. iv, U.S. Geol. Sur. 40th Parallel (King), pages 170 and 174, respect- 
ively, and both are figured on plate xvii of the same volume. 
GASTEROPODA. 
Genus RHYTOPHORUS* Meek. 
RHYTOPHORUS PRISCUS Meek. 
The type specimens of this species, which are also the types of the 
genus, were obtained from the Bear River Laramie series, near the 
mouth of Sulphur Creek, in the valley of Bear River, Southwestern 
Wyoming, in which neighborhood only it has yet been discovered. It 
is described and figured in vol. iv, U.S. Geol. Sur. 40th Parallel (King), 
page 175, plate xvii. figs. 6 and 6 a; and also in Captain Simpson’s 
Report of the Great Basin of Utah, p. 364, plate v, figs. 4 a and b. 
Under the head of Melampus antiquis, on page 24 of this volume, I 
have suggested that the species described by Meek under that name 
from the Cretaceous series at Coalville, Utah, may perhaps belong to this 
genus. Unless this shall prove to be the case, the genus Rhytophorus 
is yet known only in the Bear River Laramie series, and the only known 
species are R. priscus, the type of the genus, and R. meekii White, which 
is associated with it, and which is described in the next following par- 
agraphs : 2 
RHYTOPHORUS MEEKII White. 
Plate 30, figs. 8 a and bD. 
Shell subfusiform, spire moderately produced, nearly one-third the 
length of the entire shell; volutions about six, convex, the last one 
somewhat large, elongate, subterete, gently tapering from about its mid- 
dle to the anterior end; suture impressed, and upon the proximal side 
of and near it there is an almost equally impressed revolving line or 
narrow furrow, having the appearance of a second suture; one fold of 
the columella moderately well developed, and another less so. Surface 
marked by the ordinary lines of growth; and also, upon the spire, by 
numerous small varices or longitudinal folds, which cross the volutions 
nearly parallel to the lines of growth, and which are slightly oblique to 
the axis of the shell. These varices appear only upon the distal por- 
tion of the last volution, while they cross the entire exposed portion of 
those of the spire. 
Length of the largest example discovered, 25 millimeters; diameter 
of the body volution of the same, 12 millimeters. 
-* For Mr. Meck’s diagnosis of this genus see vol. iv, U. 8. Geol. Sur., 40th Parallel 
{King), p. 175. 
